Degeneration
by LunarNix
Summary: Through an accident with an experimental drug, Sans and Papyrus find themselves de-aged. But their bodies were not the only things changed; their memory was also altered, leaving them with only the memories of their not so pleasant childhood.
1. Chapter 1

It was getting late in underground time and Papyrus was running a little behind schedule. Granted, he had a valid reason to be. He had helped a nice older monster on the way home and it took longer than he thought.

He rushed around their small house, pulling on bits of clothing as he did. He'd just gotten out of the shower and was barely dry. He'd been a mess as he stepped in the door, mumbling something about crazy energetic children before making a b-line to their shared bathroom. Now he was almost fully dressed, shaking water out of his sockets.

"Chill out for a second bro." Sans chuckled, amused by the rare sight of his rushing brother before him.

"I simply cannot! I'm already late and would like to reduce the amount of time I am so." Papyrus said quickly, nearly stumbling over his words.

"If you keep rushing like this you'll wind up forgetting something important." Sans grinned. "And you do know that I could get you there in less than a minute right?"

"But how could you-" He paused, "Oh, your 'shortcuts.'" Papyrus pressed a hand to his head in exasperation, "gosh, it seems you were right brother..."

"Aren't I always?" Sans asked as he teleported beside Papyrus.

"No." Papyrus said shooting him a side look. "I can recall several times growing up that you have gotten us into serious trouble."

"Which time though?" Sans chuckled, "and do you have everything you need?"

"Yes, I have all my things." Papyrus fiddled with the strap holding his shoulder parts in place before adjusting his scarf. "And for your first question; how about the time after we moved to Snowdin and you managed to get us locked out of the house because you had said you had grabbed the key only to leave it on the counter."

"Whoops, guess you got me there. I hadn't learned to teleport too well yet either." Sans held out his hand for Papyrus to take. "Whenever you're ready bro."

Papyrus groaned, "I really do not like these shortcuts of yours." He grabbed his hand, feeling them get pulled through the 'void' (as Sans called it) and then standing in front of Alphy's Labs. "You know, you should join us for once. The show we're watching today might interest you."

"I'll pass, you go have fun Paps." Sans yawned lightly.

"You sure? There's a lot of space and science-related stuff in it." Papyrus grinned, knowing that he had the trap baited, "and there's a lot of robot fighting."

There was a short silence.

"I'm in." Same said, his eyelights almost like stars as he stepped closer to the door.

With that, Papyrus entered the code for the lab door that Alphys had given them and stepped back a bit to let the door open. He didn't waste a second, entering as soon as the door was open enough for him to duck inside. He checked the clock on the wall, noting that he had actually arrived just in time.

"Alphys! Undyne! We have arrived!" Papyrus called as Sans shut the door behind them.

"I'm sure they are upstairs already paps." Sans chuckled, gestering towards the stairs.

Papyrus beamed, "Ah yes, I'm sure they are!" He started towards them, shouting on ahead, "We are coming up, make sure you're decent!"

Sans froze, "What?!"

Papyrus looked back at him, "What is it brother?" He watched his brother in confusion, "Is something wrong?"

"Why would you say that?" Sans was silently still hoping Papyrus was still innocent. Though that hope was getting stepped on bit by bit.

"Come on Sans, we're adults and so are they. Acts of simple intimacy can sometimes get carried away into heavier activities." Papyrus explained, as if it was obvious, "It's no secret that Undyne and Alphys are dating so it would be a bit strange if they didn't indulge a little right?"

"Y-yeah. I suppose so." Sans was sure to have a more through talk with him on this topic later. "Let's just go upstairs Paps."

Sans stepped forward, semi-mortified at the very least but tried to push it from his mind as they stepped onto Alphy's mechanical stairs. As soon as Sans and Papyrus stepped on they started moving, carrying them both upstairs. Papyrus seemed used to the jerky way they moved, holding a hand out to Sans who just wanted the stairs to hurry up.

Once they reached the top, they found Undyne and Alphys sitting on the couch awkwardly. Undyne stood as soon as she spotted Papyrus, eagerly moving to greet him. "Sup' Papyrus?"

"Nothing at the moment but by the looks of things I was right to give a heads up hmm?" Papyrus teased, keeping a tone of 'I know what you were doing' in his words. Sans stepped past, sitting on the couch and trying to escape the reality that Papyrus knew about 'that' and all.

"Y-yeah! Good call bud." Undyne's fins drooped slightly.

"I've walked in on you two more than enough times, I wasn't just going to bring my brother upstairs while indecent things were going on." Sans clenched his teeth, his cheekbones darkening at the visual image of that exact scene.

"T-thank you P-Papyrus." Alphy's scales tinted red with blush, "y-you're always s-so c-considerate."

Papyrus beamed, "where would I be if I wasn't?" He put an arm lazily around Undyne's shoulders, "so, are we ready to start?"

Undyne grinned widely, showing each sharp tooth off. "Hell yeah!"

Papyrus laughed, sitting down in front of Sans on the floor. He preferred to sit on the floor than the couch. A habit he had since childhood as far as Undyne and Alphys were concerned.

Undyne sat next to him, but mainly just to be a little closer to the large TV on the opposite wall. "Play it Alphys! Let's get this night going!"

"A-alright." Alphys smiled as Undyne leaned back against the couch as she pressed play. The smaller monster running her small claws through Undyne's hair.

Papyrus and Undyne cheered as the precredits began to roll. The narrator speaking with a heavy tone as the backround music stayed within soft orchestral bounds. Sans perked up as the music kicked up several notches and mechanical robots flew past the screen, often fighting another with clashes of bright lights as a song of fitting intensity played. His eyelights were of stars once he noticed that those mechanical robots were in space. Space! His mind screamed at him as he watched.

Papyrus turned to look at his brother, catching the expression Sans wore, "I told you you'd like it." He spoke quietly with a amused tone.

"Right again Paps." Sans shot back with a smile. "Now hush, I'm trying to watch."

Papyrus chuckled before turning back around and leaning against the couch in a more comfortable position.

They all paid close attention after the opening passed, hooked into every word. There wasn't many episodes on the disc but Alphy's had luckily found the complete set for the first season in one box. It was rare and Undyne hadn't seen her that riled up in a long time. Papyrus stood and changed the discs each time, double-checking the numbers printed on each one before switching them out.

By the third disc, Undyne had changed the discs as Papyrus had dozed off lightly. Surprisingly though, Sans was still wide awake, gently rubbing a hand over Papyrus's skull. Papyrus sleeping quietly as the current disc played itself out.

"He's so d-different while sleeping." Alphys whispered, not wanting to wake him. She carefully stood, stretching her limbs. "Ooh, my sc-cales are stiff."

"I'm not looking forward to moving either." Sans sighed, slowly stretching out, grimacing each time his bones cracked.

Undyne laughed, "Pap looks his age while he sleeps. Despite everything, he is still so young."

"So are you. I'm older t-than you by at least t-ten years." Alphys added, motioning for Undyne to follow her. "You are only about t-two or three years older t-than Papyrus."

"And Sans is just a couple years older than me." Undyne said as she and Sans stood and followed Alphys into the main lab, "He had said before that he was four years older than Papyrus."

"Yup, that I did." Sans replied, looking at the large screen that had various camera locations around the underground.

Alphys walked over to the little kitchen area her and Undyne had set up the month before, "It's no wonder you two are so close."

"That's not the only reason." Sans said in passing.

Undyne leaned against the table, poking at a couple of the test jars. Her nails making little sounds against the glass, "I know I'm not the type to be askin' deep questions and all but...I wonder what exactly happened when you two were younger to make you get that close."

"It's nothing that I personally like to talk about. But I can tell you this much," Sans leaned against the table. "Check me."

Undyne looked at him, "What's that got to do with anything?"

"Just do it, both of you," he said glancing at Alphys. There was a moment of hesitation before they did so.

Sans Serif - 1/1 hp

 _* loves his brother very much..._  
 _* a bit uncomfortable..._

"1 hp...I've heard Paps talk about it in passing but I haven't seen the proof myself." Undyne said, lowering her hand.

"H-how are you alive!" Alphys added in semi-shock.

"Papyrus." Sans sighed, "He's always been cautious. Even more so around me. But how do you think I got this way, I didn't always have 1 hp."

Alphys thought for a moment, a flash of understanding passing over her face at the same time as Undyne's. "What happened to you two?"

"And that is where I stop." Sans chuckled, "I won't say that part. Neither will Paps. It's a...sensitive topic."

Undyne went to speak but promptly shut her mouth and sighed. She couldn't argue with him, he always found his way on top. "Alright, alright. We won't push ya about that but I'm still a bit worried about that hp of yours."

"If I could change it back to how it was I would" Sans hummed, "I've tried everything short of killing someone. Which I would never dare kill anyone just to test my theory."

"I m-may have a way...but it's experimental." Alphys said after a moment.

Sans laughed amused, "Isn't everything you make experimental?"

Alphys nodded, "I have n-never used this before though. It works with the soul."

"Well it's not like we're going to abuse the drug." Undyne grinned, "what is it exactly?"

"It's a l-liquid injection. I have n-needles specifically for skeletons t-that I found in the old labs." Alphys seemed a bit proud of that statement as she dug around for the syringes. It only took a few minutes to find them. "I'm n-not so sure of this though..."

"A drug to bring up my hp? Alphs, I'm willing to take that risk." Sans sighed, "besides, even with my single hp, I haven't found something able to take it away just yet so I'm sure your drug won't mess with it."

"Sans?" A sleepy Papyrus called into the lab. "Oh! There you are."

"Sup Paps. How was your nap?" Sans grinned.

"It was nice," Papyrus yawns a bit before he caught sight of the needles, "what are you going to do with those?" His tone dropped a bit as he looked between them and his brother.

"Alphys may have a way for my hp to go back up." Sans explained, stepping into Papyrus's view of the needles.

"Sans. This is dangerous!" He argued, "Even HE couldn't bring your hp back up! What makes you think she can?!" Undyne and Alphys shared a glance as Sans stiffened.

"Because she isn't HIM." Sans replied, "I want to take the chance so you don't always feel like you have to protect me!"

"I-" Papyrus turned away, his expression in a grimace. He knew that Sans was right. He sighed, "fine...fine. However there is one condition...I take the drug with you."

"But you hate needles." Sans replied.

"So do you." Papyrus removed a glove, showing the various chips along the bone along with a large hole in the middle of his hand. "Maybe it has a side effect that can heal these."

"Paps..." Sans turned and looked at the other two, "I guess that's how it'll be."

"B-but-" Alphys was reluctant to use her serum on one of them and now that Papyrus wanted to join, she wasn't sure of it.

"It'll be alright Alphs, I'm sure that those two will be fine." Undyne said as Alphys moved to measure out the amount for each of them. "You're so amazing that I'm sure things will be alright."

"You s-sure? Their minds may g-get messed up for a while...since it affects that part of the soul." Alphys said, "I've never tested it so I don't know the s-side effects."

"If there are any that are negative I'm sure you could help them." Undyne said with confidence, taking the needles from Alphys carefully. "Where do you inject these?"

"On the back of their hands. That's what the notes beside these syringes had said was the best place for a skeleton injection." Alphys said as Undyne left the room following after Sans and Papyrus that had gone to sit on the couch.

Undyne knelt down before the two, carefully reaching for Papyrus's right hand, "Nice and easy." She hummed. Papyrus clenched his teeth, looking everywhere but his exposed hand. She suppressed a gasp at the sight of several chips and scars in his bones. She could see each detail up close that she couldn't before. Even little dots of what looked like needle marks that didnt heal. But that's not what surprised them the most; the sheer damage the large hole in the middle of his hand looked like it had taken. The hole looked old and grown into. But not so cleanly cut and smooth. In fact, it was rough and scarred. She took off his other glove, finding the same marks.

Alphys shared a concerned glance with Undyne as she prepared to inject Sans. They nodded and gave the injections quickly and at the same time. Both skeletons gave signs of discomfort at the needles but their postures relaxed once more after Alphys put a healing gel of sorts to the marks.

"That wasn't so pleasant." Papyrus groaned as Alphys took the needles back into the other room. Undyne noticed the brothers relax a bit as the items left their line of sight.

"That's less painful than I remember." Sans muttered in passing to which Papyrus nodded.

"Have you two had to have shots before?" Undyne asked, "I don't think I've ever seen you two sick before."

"Something like that." Papyrus admitted as Alphys returned to the room.

"You t-two need to be hooked up s-so I can monitor your health." Alphys said as she waited by the door. "Come this w-way."

Papyrus and Sans stood, following her to one of the side rooms that she had set up for sick monsters who needed emergency care. There were three beds in this one with a monitor next to each. They entered and the women watched as Sans and Papyrus hooked themselves up quickly, almost as if by physical memory.

"Have you two actually stayed here before?" Undyne asked as she sat on the empty bed just inside the door. "For as much as I hang around Alphys, she, or anyone else, doesn't usually put those on so fast."

"Sorry Undyne, that falls into the 'don't ask' category." Sans grinned as he glanced over to a none too happy Papyrus.

She frowned a bit, not at all satisfied with that answer. Alphys checked to make sure the devices were secure before turning the machines on.

Sans 1/1 hp

 _* anxious yet excited_

Papyrus 680/680 hp

 _* anxious for his brother_

"You two just r-relax, we have to w-wait for the d-drug to kick in." Alphys said as she watched the monitors for any changes.

"Alphys, do you mind if I get some water? This room is a little warm." Papyrus asked as he got comfortable.

"Yeah, now that you mention it, it is a bit hot in here." Sans said, absentmindedly playing with the drawstrings of his hood.

"Y-yeah! I can t-turn the temperature d-down too if you like." Alphys said as she moved away from the monitors for a moment to fiddle with the thermostat she had built into the room. "Undyne c-can you get them s-some water?"

Undyne stood, looking a bit anxious since Papyrus started fidgeting with his scarf, pulling it away from his neck. He never messed with his scarf no matter how hot it was. What unnerved her more was the thin scars that he hid behind his scarf seemed even more visible beneath the room's bright lights. She returned to the room in record time with two water bottles that were freezing cold to the touch.

"Thanks Bass." Undyne groaned at the nickname he'd given her as she tossed him to bottle, a smug smile on his face as he caught it.

"Thank you Undyne." Papyrus said as Undyne handed him his. Alphys returned to her seat, holding her coat close to herself. The room had grown frigid and being a cold-blooded monster, she felt the effects.

"T-that's as cold as I can make it g-guys." Alphys said, rubbing her arms a bit.

"That's alright Alphs." Sans sighed, shrugging his jacket off one shoulder. "We've lived in Snowdin for too long, the cold has really chilled us to the bone."

Papyrus groaned, pressing a hand over his eyes, "Really Sans?"

"Don't be so hot-headed Paps." Sans grinned.

"Shut up Sans," Papyrus sighed with a small smile.

"But your smiling."

"I am and I hate it."

Undyne chuckled a bit as Alphys kept watch on the info below their health. It was changing and she chuckled.

Sans - 1/1 hp

 _* amused_

Papyrus - 680/680 hp

 _* irritated but amused_

Everything seemed to be going smoothly, she wondered when the drug would kick in. She would wish later that she hadn't done so.

Papyrus and Sans sipped at their water absentmindedly, their bottles around half empty when they started to pant. It was gradual, they could feel the temperature slowly rise in their bones. Alphys had looked up when they shifted a bit to feel a cooler part of the beds they sat on.

Sans - 1/1 hp

 _* uncomfortable_

Papyrus - _680/680 hp_

 _* uncomfortable_

"Are you t-two alright?" She asked. Undyne perked up a bit, having relaxed against the wall near Papyrus.

"It's getting hot again." Papyrus groaned a bit, glancing at his brother who had all but removed his favorite jacket.

"Hot is an understatement." Sans sighed, moving so that his legs were dangling off the side. "I think that drug of yours is kicking in."

Undyne's fins drooped slightly as she paid close attention to Papyrus who had brought his knees up to his chest, resting his head against them. "Y-yeah...it's working alright." Papyrus's voice was strained but amused.

Sans looked up at him concerned, his eye glowing with his mixed magic. "Pap. You know you didn't have to take a dose too."

Papyrus chuckled, looking at him, his own eyelights glowing, "Yeah, I did. Because on the off chance something happened..." Papyrus didn't say anymore, his point was conveyed between them as the two women thought about what he meant. Not that there was much time to as both skeletons soon made noises of distress as they doubled over, clutching their chest.

"T-that really fucking-" Sans panted. "Holy shit!"

"Watch your language!" Papyrus leaned back against the wall, trying not to curl in on himself, it wouldn't help anything but to restrict his soul from pulsing properly. The burning was intense, filling every bone. But nothing compared to the pain in his soul. He pressed a hand against his chest, coaxing his soul out.

Papyrus's eyelights dimmed out as he held his soul gently, hiding the cracked surface from view. He had gotten the marks years ago though he knew Sans was far worse. Papyrus pulled himself away from his memories and examined the small bundle of magic for any new cracks. There were some but they were very thin. He sighed in relief as he put his soul away.

Undyne sat next to him, "are you alright? Your health went down some."

"How much?" Papyrus asked, still trying to push the pain to the back of his mind as he checked how Sans was doing. Not much better he decided.

"It's at 340 right now." Undyne said and Papyrus chuckled.

"I'm fine then." He looked at Sans's stats, that single hp was still intact but he didn't know for how long. He got up, careful not to disturb the monitor as he sat next to Sans. "Sans, let me see your soul."

Sans looked up sharply, "What? No I'm fine!" He could protest all he liked but Papyrus would be getting it and he knew that.

"W-why do you n-need his soul?" Alphys asked.

"He knows exactly why." Papyrus said, giving his brother a look that clearly spelt out 'no funny business.' "And he knows that I'll get it one way, or another." He added a bit quieter as more of a warning.

Sans tried to protest once more but just sighed and gave in, speaking just above a shaky whisper, "just don't let them see it."

"I'm not going to." Papyrus placed a hand over Sans's chest, gently withdrawing his soul. Instantly lighting up his hands in healing magic, half to hide the soul from view and half to heal some of the new cracks marring the surface. Sans gasped as the magic touched the fresh cracks, filling the new chips up one by one.

He had just started healing a new crack when Sans leaned his head against him, clenching his teeth in pain. The teal of his magic expanding outwards from his soul. The flame like magic licking at Papyrus's fingers. It didn't hurt. Rather pleasant to the touch.

"Sorry, magic isn't listening to me." Sans panted as he tried to reel it back in. "Give me a minute."

Alphys bit her lip hard, she was praying to every star in the underground that she didn't just give her two best friends a death sentence. She watched the two suffer before her, her mind drifting back not too far in the past to her DT experiments with a shiver.

Papyrus grit his teeth as a wave of pain washed over him, orange tints making their way into his green healing magic. He focused hard but his magic blew up in his face in a burst of energy. No damage was taken on the two outside of their surprise. Papyrus stared in shock at his hands, "That's new."

Undyne narrowed her eye, Papyrus had almost perfect control over his magic, she had never seen it do that unless he was dispersing many bones at once. She looked back at Alphy's with concern, noting how closely Alphys was watching the monitor.

"Alphys...if you have a counter to this drug...it may be a good idea to get it ready." Undyne said in worry.

A moment later, (no sooner than she had finished speaking) the monitors alarms sounded as Papyrus and Sans tensed up. Alphys watched as their health fluxuated with horror. Sans's hp bar seemed glitched as the monitor couldn't read his health. Papyrus's dropped sharply, leaving him with just 20 hp and kept dropping.

"Alphys!" Undyne shouted as the brother's cried out. Neither women had ever heard them sound like that before. The brothers clutched onto one another tightly, grounding one another. Their magic licking at their bones as they tried to keep it contained. "Isn't there something you can do to help them?!"

Alphys looked at her with fear before she thought of something, "yes! Yes I do have s-someth-thing I c-can do!" She rushed out of the room, leaving Undyne to watch over the two skeletons. They had taken to leaning against one another for support as their magic violently flickered to life around them.

Undyne watched in concern and horror as there was a bright flash of multicolored light and both of them vanished. Only the overwhelming warmth of the sheet where they sat giving any sign that they were there to begin with.

"SANS, PAPYRUS!"

-  
To Be Continued...  
 **-**

 **Thoughts? Questions? Comments?**

 **I love hearing your feedback even if it's just a typo error I missed. Thanks for reading!**


	2. Chapter 2

_Undyne watched in concern and horror as there was a bright flash of multicolored light and both of them vanished. Only the overwhelming warmth of the sheet where they sat giving any sign that they were there to begin with._

 _"SANS, PAPYRUS!"_

 _Alphys had just entered the room as the two vanished. The light struck Alphys as similar to the magic flash that Sans uses to teleport. She had almost dropped the syringes she held in shock at the sight._

 _"W-what just happened?" Undyne stammered in surprise and worry._

 _Alphys couldn't possibly give her an answer. She knew something may have been off but hadn't had the counter drug in the room and on hand. She may have just dusted two of her closest friends._

 _Alphys shivered at the thought._

 _"Alphys, don't cave in now. We need to look for them." Undyne said sternly but caring. She walked over and rubbed Alphy's arms gently, soothing the scientist. "We need to look for them." Undyne repeated much gentler._

 _"O-okay. Let's check up here first, then the labs downstairs." However, she could only hope that they weren't down there._

-  
Elsewhere  
-

It was dark. Far too dark for their liking. The cold room seemed even colder as they snuggled up to one another for whatever faint warmth they could get. The last thing they remembered was sitting in their cell after today's magic lesson. But they had a feeling of unease that disturbed them. Both brothers were alert despite their physical exhaustion.

"Huh? Where'd the lights go?" One asked, timid and frightened. "He always leaves one on outside our room."

"I don't know. He never shuts them all off like this. I wonder if it's something with the core." The other replied, trying to keep a more confident and cheerful tone. "It's so dark! Wow!"

They tried to light up the room a bit with what magic they had - not at all happy that there room was plunged into complete darkness - but their magic's glow was too faint. Any light they produced barely lit up their faces.

"I have another question...w-what are we wearing?" The younger said as he looked down at his flashy clothing that were far to large for his body. "What happened to the other clothes we had on?"

"I don't know but this coat is so warm!" The other said as he hunkered further into the faded jacket around him. He looked up at his brother, "Hey, that scarf looks good on you Papy."

"Does it?" Papyrus replied, with a somewhat strained smile. "Do you think he gave us some drug along with our normal shots? What is going on?" He began to tear up, "What if we die Sans!"

Sans wrapped his arms tightly around his brother, a strange feeling in his soul, "We won't die Paps. We've survived everything so far, we can survive this." Papyrus nodded as Sans wiped his tears away. "And do you know what else?"

"What?" Papyrus sniffled.

"Hear that?" Sans said, shushing him. The sound of sharp footsteps could be heard from above them, faint but clear. Similar to the frantic steps they hear when the Core malfunctions.

"I think someone's upstairs. Someone who isn't that evil man." Sans grinned widely, his eyelight shining brightly. "Maybe they'll help us!"

Papyrus looked skeptical, "Remember last time?"

Sans nodded, a hand moving over his eye."Maybe this time will be different."

"You'd better hope so." Papyrus huffed under his breath. He moved to a corner of their cot with mild difficulty from their oversized clothing and laid down. His body ached all over and he didn't want to deal with it in any way, shape, or form.

Sans watched his brother lay down with a sigh. Lately he had been trying to keep his hopes up but it's getting harder with time. He knew that Papyrus wasn't as optimistic as he was anymore but he hopes that he'll turn that around one day.

As the older brother, that's all he could hope to do. But there was a lingering feeling of wrongness, like things weren't supposed to be this way. A feeling he couldn't place his fingers on.

He shook his head and smiled once more, "Hey Papy?"

"What?" Papyrus yawned, turning his head his way.

Sans's grin didn't faulter, "If all the lights are out, doesn't that mean the door can open too?"

Papyrus sat up as he spoke, "It _is_ run by the power from the core as with everything in this building." He recalled that man saying. "It's possible there was a problem with the core."

"Let's try the door then." Sans lit his eyelight up a little brighter to see the floor, walking to the door and taking his brother with him.

"Are you sure about this?" Papyrus questioned, gripping his elder brother's hand a bit tighter.

"Do you want to get out and see what the outside world is like?" Sans replied, "Come on."

Sans reached for the handle, slowly turning it. He could hear both their souls anxious beats as the handle turned fully. "Holy stars...it's actually open!"

They were both cautious as the door opened the rest of the way on its own, looking old with rust and disuse. Why though? They had just seen it clean and bright a mere hour before...didn't they?

Sans felt that something was definitely off. The building had the sense of pain and experimentation as usual but there was something else. Something he couldn't place and it made him move closer to Papyrus.

"Be careful and quiet," Sans muttered. "Something feels wrong."

"Nothing down here ever felt right." Papyrus noted.

Sans glanced back at him before turning back towards the hall and stepping through the door.

They noticed then that there was still some power to the place, the little wall screens all lit up dimly, the halls just barely illuminated enough to walk through. They took small steps in the direction they knew the exit was. After their previous attempts to leave, they had found out that it was an elevator a few halls past the doctor's office and the training rooms. They had never gotten this far as far as they remembered so when they stood before it, they had an even heavier feeling of unease.

"Why isn't anyone else here?" Papyrus asked quietly.

Sans was at a loss for words, just shrugging in response. He looked around the darkened room, his eyelights glowing a soft blue. He noticed a bit of movement in the corner as he was about to press the button to call the machine down to them.

A sharp clang of metal hitting the ground behind them startled them both, magic spiking up almost instantly in defense. Papyrus stepped closer to Sans in fear and his brother grasped his hand in response. They stood there, staring in the direction of the noise and waited for a single sign to defend or flee.

A soft growling grew closer to them as well as the sound of a liquid dripping that sounded suspiciously like some sort of gel. A large shadow moved within the reach their magic's glow, illuminating a large misshapen figure that seemed to melt and reform as is continually warped.

"S-Sans?" Papyrus sniffled lightly, gripping his brother more tightly as they were facing a creature they have never seen the likes of before. Unknown, spine-chilling, and leaning right over them.

They found themselves in a staring contest with the beast, unwilling to engage in any sort of conflict they were sure they would lose. They watched in horror as the creature seemed to lean further forward and release a guttural rumble similar to a howl, loud and foreboding.

-  
Upstairs  
-

Undyne and Alphys had searched everywhere in the lab, both petrified and losing hope.

"Where are they!?" Undyne spoke with distress. She turned to Alphys with an expression of unease. Her thoughts reflected in Alphy's eyes.

"We've checked everywhere."

"Isn't there any place we haven't checked?"

"The old labs..." Alphys replied shortly, her eyes widening. "If t-they are really d-down there, we need to f-find them now!" She was hasty in reaching the only working elevator downstairs. Undyne was right behind her, hoping they hadn't lost their friends forever.

Just as the elevator opened, the ground rumbled beneath their feet, a loud jumbled roar reaching them. They shared a quick glance at each other, before shuffling into the elevator. Whatever that noise came from, it didn't sound good.

They hoped that when the door opened again they wouldn't see any dust.

When the elevator reached the bottom, there was a moment of pause where everything went still as they held their breath.

A short ding was the only warning they received before the doors opened.

There, in front of them, was the giant dog amalgamate leaning over what looked like two children.

Sans had heard the elevator ding, knowing the way to their escape was right behind him. But he dared not let his eyes wander from the creature, not knowing what it may want to do outside of gooping all over them.

A loud shout echoed past them, seemingly aimed at the big creature. It's attention was drawn away from them, to whoever had stepped forwards and shouting at the creature like it was a misbehaved pet.

Sans made a quick bolt for the elevator, making sure to pull Papyrus along. Their magic sparking viciously across their bones from the high threat of danger. They were both covered in black, slimy goop of some sort.

"You okay bro?" He asked his brother, not caring about the scientist who was watching them with mixed bits of curiosity and shock.

"Yeah, this stuff is really weird, do you think it'll come off?" Papyrus replied, examining the goo that was on his scarf.

"I don't know." Sans looked up at the yellow monster in the elevator with them and hid Papyrus behind him. "Who are you?"

"M-me?" Alphys stammered, still in shock to how two young skeleton children ended up in the old lab to begin with. "I'm doctor Alphys, the royal scientist."

Papyrus spoke up, "But I thought Doctor Gaster was the royal scientist."

"Yeah, it's a bit odd really. G wouldn't have given his title up all willy nilly." Sans added.

"But it's t-true!" Alphys tried to defend as Undyne returned to their little group.

"That one sure is a handful," She sighed before noticing the brothers. " and when did they get in here?"

Sans let his magic levels rise, his eyelights glowing bright in warning. She looked like she wasn't the nicest fish in the sea and he didn't want her any closer to his brother.

"What's your problem?" Undyne said, kneeling down to their level. "Wow you two are filthy. Al, take us up, we need to figure out how and why these two were down there."

"H-hold on a m-moment Undyne." Alphys stammered, "D-did you two s-see anyone else d-down here?"

The brothers frowned, glancing at each other. They shook their heads as Sans spoke, "No, we have only ever seen the doc and a couple assistants. He should've been there by now."

"Um, is there someone you're looking for?" Papyrus spoke in a quiet voice behind his brother. "We didn't see anyone though."

Alphys sighed, reluctantly pressing a few buttons to raise the elevator back up. "A pair of skeletons, j-just like you t-two."

"Wow, so there are more of us?!" Sans smiled, a sudden energy taking him over. "How exciting!"

Papyrus shied back further, "what if they were bad too?"

"Nonsense! Those two knuckleheads are the best skeletons in the whole underground!"

Papyrus tilted his head, "What's a knucklehead?"

"Sounds strange." Sans hummed, "can't say doc ever mentioned those."

Undyne and Alphys gave each other concerned glances. "Just how long have you two been down there?"

Papyrus looked at his brother who replied, "dunno. We don't exactly remember being anywhere else."

"We were 'born' here." Sans replied, adding quotes. "Though we weren't born in the traditional sense as far as I understand."

The elevator doors slid open, letting them get off the lift. The two adults went first, the brothers right behind them. Sans glanced around, a dim feeling of deja vu entering him. Though, he couldn't seem to ever remember being here. He struggled to think back, only tracing the lab downstairs.

"Brother?" Papyrus tugged on his arm, jerking him back to present. "you okay?"

Sans hadn't even realized that he had stopped walking. "Sorry bro, I'm alright, I've just got some weird feeling."

Undyne led them to the main area of the lab, a table and a few chairs having been set up previously. Alphys had stepped into another room, returning a minute later with wet towels and a bowl of warm water.

"H-here, so you can c-clean off." Alphys said, setting them on the table. She stepped back, taking a better look at the two, their clothes were far to big for them and hit a chord of familiarity.

Sans shrugged off his jacket, a bit disappointed to loose the warmth the oversized coat brought him. It was all covered in goop, same with every other inch of them. He sighed, helping Papyrus unravel the long scarf before helping to clean his baby brother up.

Undyne watched them, eyeing the coat and scarf they removed. Both identical - minus the goo - to their missing friend's favorite articles of clothing. Her eyes narrowed, "Are you sure you two didn't see others down there with you?"

Sans didn't look up from where he was trying to get the goop from between Papyrus's hand bones, "yeah, we didn't see anyone. I have no reason to lie to you."

"Undyne, a-aren't those San's and Papyrus's things?!" Alphys exclaimed suddenly, "how do you have them?"

Papyrus shied closer to Sans, speaking softly to his brother, "brother, how do they know our names?"

This didn't go unmissed by the Captain of the Royal Guard however, who proceed to nearly smash the table as she slammed her hands onto it. "WHAT WAS THAT?!"

Papyrus whimpered, on the verge of tears from the outburst. "I'm sorry!"

Sans wrapped his arms tightly around his brother, "he asked how you knew our names. We have never told anyone nor were we able to."

Undyne suddenly went pale, "I think I need a moment to process this." She slipped into the other room, sitting on the couch, leaving Alphys with the boys.

"T-those are the names of the friends w-we were l-looking for." Alphy's eyes widened in sudden realization. "Oh stars...what have I done?"

* * *

 _ **a/n: okay... I've done it...I've finished a chapter, it's short but its an update. Also, a few other stories should be updated shortly. (at least within the week hopefully)**_


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